The embodiments of the present invention relates generally to pyrotechnic gas generators for vehicle occupant protection systems, and more particularly to such a gas generator having a cushion interposed between a gas generant material and another portion of the gas generator to help prevent fracture of gas generant grains or wafers due to vibration or impact.
A concern in the performance of gas generating systems is repeatability of performance of the gas generator. Propellant or gas generant springs or cushions are employed in some gas generating system designs to prevent fracture of the propellant due to contact between the gas generant material and the interior of the gas generating system housing. This aids in maintaining a relatively constant propellant surface area of combustion.
Additionally, certain propellants may be hygroscopic wherein the absorption of humidity and/or water may inhibit expected burn characteristics and therefore may result in performance variability of an associated airbag cushion during a crash event. Even though useful in preventing the fracture of propellant, propellant springs or cushions also add to the manufacturing complexity and cost, and to the weight of the overall gas generating system.
Also, in some gas generating system designs, flammable gases may be produced by the heat-related decomposition of certain cushion materials in contact with the gas generating system housing, due to the elevated temperature of the housing after system deployment. It is desirable to minimize the generation of such gases.